Pressure differential safety interlock system



Jan. 12, 1965 T. STRAUSS ETAL 3,165,121

PRESSURE DIFFERENTIAL SAFETY INTERLOCK SYSTEM Filed July 27, 1962 INVENTORS TH EODOR STRAUSS WILHELM BACHMANN "a. am

A TTUENE) United States Patent 3,165,121 PRESSURE DEFFERENTIAL SAFETY TNTERLGCK SYSTEM Theodor Strauss, Eerenbostel, Hannover, and Wilhelm Bachmann, Godshorn, Hannover, Germany, assignors to Westinghouse-Bremsen-Gesellschaft m.b.l-l., Hannover, Germany Fiied July 27, 1%2, Ser. No. 212,95 Claims priority, application Germany Nov. 3, 1961 f 2 Claims. (Cl. 137625.41)

This invention relates to pressure differential safety interlock apparatus for va pluratlity of control valves utilized to control a single operating device.

In the propulsion of ships, it is common practice to control the angle of incidence of the propeller blades either pneumatically or hydraulically to thereby control direction of travel and speed of the ship. This control of the propeller occurs by means of a pressure actuated adjusting device which is usually located in the propeller shaft alley and controlled by a plurality of control valves, one .of which is located on the bridge control stand and the other is located on the engine room control stand. The selection of the operating control valve to be effective is under the control of a multiple position cock or similar device usually located in the engine room which operably connects either the, one control valve or the other control valve with the adjusting device.

By means of this arrangement just described, it is possible that control of they adjusting device may be attempted to be applied undesirably by both control valves simultaneously. For example, if while the ship is moving the control valve on the bridge control stand is adjusted to operate to supply a certain fluid pressure to the adjusting device by Way of the multiple position cock to give a propeller angle of incidence ofa positive angle, and concurrently the multiple position, cock is repositioned such that fluid under a different pressure is supplied by the control valve on the engine room control stand to adjust the angle of incidence of the propeller to a negative angle, a severe damaging shock on the driving engines and more particularly the propeller shaft and gears associated therewith would occur.

The present invention eliminates the possibility of changeover of the multiple position cock unless the control pressures supplied by both of the control valves are equalized. A dillerential between the pressures supplied by the two control valves renders the multiple position cock inoperative to transfer the control of the adjusting device from the one'control valve to the other.

According to the present invention, the manually operated rotatable plug valve of a multiple position cock is locked in one position if the fluid pressures which are supplied thereto by two control valves are of unequal degree as determined by an equal pressure valve, and said plug valve in the multiple position cock body is unlocked and can be repositioned if the fluid pressures supplied thereto are of equal degree.- The multiple position cock can therefore be repositioned under the control of an equal pressure valve only when fluid pressures supplied (thereto from the two control valves are substantially equal. The equal pressure valve has a diaphragm thereably mounted therein may align with the locking groove in activated on one side by the fluid pressures delivered from one control valve, and on the other side'by the fluid pressures'delivered from the other control valve in a manner that when the fluid pressures on both sides ofsaid diaphragm are equal, a source of fluid under pressure, such as a supply reservoir, is connected to a locking "Ice valves and the multiple position cock under the control of an equal pressure valve.

FIG. 2 is an enlarged diagrammatic sectional view showing details of the equal pressure valve of FIG. 1.

Description Referring to FIG. 1, the apparatus includes a bridge control valve 1, an engine room control valve 2, a pressure dilferential operated valve means referred to hereinafter as an equal pressure valve 3, and a multiple position cock 4, all interconnected by appropriate piping supplied with fluid under pressure from a supply reservoir 5. The bridge control valve 1 is manually operated by a handle 6 wherebysupply of fluid under pressure from the reservoir 5 flows from a pipe 7 through said control valve, as indicated by.a dotted line, to a pipe 3 at a pressure determined by the positioning of the said handle fi'from a full pressure position shown to another position (not shown) whereby pipe 8 is connected through said control valve [to atmosphere at a port 9. The engine room control valve 2 is manually operated by a handle 10 whereby fluid under pressure is supplied from the reservoir 5, pipe 7, a pipe 11, through said control valve, as indicated by a dottedline, to a delivery pipe 12 at a pressure determined by the positioning of the handle 10 from a 'full pressure position shown to another position where said delivery pipe 12 is connected therethrough to atmosphere at an exhaust port 13.

The multiple position cock 4, in this instance a twoposition, three-way cock, includes a valve body 14 and a plug valve 15 whereby said plug valve 15 is rotatably positioned within the valve body by movement of a valve handle 16 connected to the plug valve by means not shown. 7 The valve body 14 is provided with three radial passages 17, 18 and 19, passages 17 and 19 connecting to the delivery pipes 8 and 12, respectively, while passage 18 is connected to a pressure actuated adjusting device not shown) for adjusting the pitch or angle of incidence of the propeller blades according to the degree of pressure supplied thereto, the details of the adjusting device being not necessary to an understanding of the present invention. Also included in the valve body is a guide slot 20, explained hereinafter. The plug valve 15 has a recessed or feed groove 21 of a length to, selectively connect either passages 17 and '18, or passages 18; and 19 (as shown in broken lines), according to the rotative position of said plug valve. 'Two locking slots22 and 23, explained hereinafter, are also in the plug valve 15.

Associated with the .multiple position cock 4 is a locking cylinder 24 suitably mounted by means (not shown), such that a piston stem 25 of a piston 26 slid- 20 to extend therethrough' into one or the other of the locking slots 22 or 23. The piston 26 in said locking cylinder forms a fluid pressure chamber 27 on one side thereof and a spring chamber 28 on the other side thereof for housing a spring 29. The chamber 27 is connected by a pipefiil to the equal pressure valve 3. The spring chamber 28 is vented to atmosphere at a port 31 to permit free movement of the piston 26 when subject to fluid under pressure in the chamber 27.

The equal pressure valve 3, besides being connected to the locking cylinder 24 by way of pipe 30 as previously described, is also connected to the passages 17 and 19 in the valve body 14 of the multiple position cock 4 by pipes 32 and 33, respectively, and to the supply reservoir 5 by way of pipe 34 and pipe 7. The equal pressure'valve 3 is comprised of ahousing 36 divided intotwo' portions joined together by suitableme ans such as bolts 37 through flanges formed thereon to secure therebetween a dia phragm 38. The diaphragm 38 separates the interior of the'housing into two chambers, chamber-39suppliedwvith,

their right-hand positions.

fluid under pressure from pipe 32, and chamber ill supplied with fluid under pressure from pipe 33. An axially movable rod 41 is connected through the center of the diaphragm at two face plates 42 and on either side of said diaphragm, the ends of said rod slidably extending into bores 44 and 45 formed in the housing. The face plates 42 and 43 are secured together with the diaphragm 38 between them by any suitable means such as rivets orscrews with either one of said plates being secured to the rod 41 as by welding, to thereby effect transmittal of any movement of the diaphragm to the rod 41. On the lower side of; the diaphragm 38 within the chamber as are positioned two movable spring cups 46 and i7 slidably mounted within a groove 4-8 in the internal surface of the housing and secured therein by a snap ring 49. interposed between the two spring cups under compression and encircling the rod 4 1 is a spring which exerts a biasing force outwardly on the spring cups in a manner to position the spring cups at the outer. edges of the groove .48

to maintain the diaphragm 38 in-its centered position as shown. A locking plate 51. encircles the rod ill below one of the spring cups 4 7 and is secured to said rod such that raising movement of said rod will be opposed by the spring 59 acting against the spring cup 47 and locking plate 51. Lowering movement of the rod 41 is opposed by the spring 5% acting against the spring cup 36 and face plate 43.

A third chamber identified herein as the regulating chamber 52. is formed within the chamber 39 on the upper portion of the housing as, said chamber comprising a slide valve. bore 5'3 and a spring chamber. 54. Slidably positioned within the slide valve bore 53 is a hollow piston stem 55 of a piston 56. The hollow piston stem-S5 acts as a slide valve in the bore 53 and contains a chamber 57 with an outlet .53 on the sliding portion of said stem to positionably align with an exhaust port 59 in the housing 36 when the piston and piston stem are moved to their left-most position, as shownin the drawing and explained hereinafter, The chamber 57 also has an Outlet or exhaust port 69 in the face of the piston 56 which opens into the spring chamber 54. A spring 61 is interposed between the lace of the piston 56 and a portion of the housing 3 3.} An intake port 63 is also formed in the portion of the housing 36. An intake and exhaust valve 64 is located in the spring chamber and comprises astem 65 withan exhaustvalve ball on one end thereof adaptable to seat in theport6lin the face of the piston 56 and an intake valve ball s7 on the other end of the stem 65 adaptable to seat in the intake port 63. A spring 68 biases the intake and exhaust valve towards the face of the piston. or in a left-hand direction as seen in the drawing. Intake chamber ostconnects .the intake port 63 to the pipe 34.

Suitably attached to thehousing 36 to the left of the piston 56 and hollow piston stem 55 is a pivot mounting 76) to which is pivotally. secured a two-arm crank lever i The upperend of the twoarrn lever '71 is formed in a ball-shaped knob 72 to abut the end of the piston stem 55. The lower arm of the two-arm lever '71 is formed in a ball shaped knob 731m ride on a two-surface cam 74 on rod 4i. Cam i i-has a high'surface '75With two tapered surfaces on either side of the high surface 75 decreasing in diameter towards the diameter of the rod 41. The upper taperedsurface is identified as surface '75, the lower. tapered surface being surface 77. This cam is securely mounted in an encircling manner about the rod 4-1 foroperational purposes described hereinafter.

Operation In operation, the apparatusshown in FIG. 1 is supplied with fluid under pressure from the charged reservoir 5 via the pipe 7 and through both the bridge control valve 1. and the engine room control valve 2 via pipe 11 when I both said controlvalves l and 2 are in their respective full pressure positions '-as sh'own, with handles 6 and id in With the handles 6 and-1Q positioned as just described, equal fluid pressuresare supplied by pipes S and 12 to pipes 32 and 33 respectively, thereby effecting an equal fluid pressure supply to chambers 5% and on opposite sides of the diaphragm 38 of the equal pressure valve 3. With equal pressures in the chambers 39 and td, the equal pressure valve 3 is centrally positioned, as shown, to establish communication between the pipes 34 and 3t? in a manner now described. Equal pressure on opposite sides of die diaphragm 33 permits the spring 59 between the spring cups 46 and 47 to position the diaphragm and connected axial rod 41 to a center position as shown, wherein the high surface 75 of the cam 74 on the rod 41 engages the ball-shaped knob 73 of the lower arm of crank lever Fl. With the high surface 75 of the cam 74 engaging the crank lever 71, said crank lever is pivoted clockwise about the pivot mounting iii in a manner that the ballshaped knob 72 engages the hollow piston stem of piston 5s and moves said piston and stern to a right-hand position against the force of spring 6i, as shown. With the piston 56 in its righthand position, the face of the piston 56 engages the exhaust valve ball es at the port 6% to close said port 6% and also move the entire intake and exhaust valve 64 to the right against the force of the spring 68 to move the intake valve ball 6'7 away from the intake passage as to thereby permit fluid under pressure to flow from the reservoir 5, pipe 7 and pipe 34, through the chamber 69, passage 63 and chamber 5 to the pipe 39.

Supply of fluid under pressure to pipe 3t) as just described establishes a supply of fluid under pressure to the chamber 27 of the locking cylinder Ed to effect movement of the piston 26 and piston stem 25 to a left-hand position, as shown, in opposition to the force of the spring 29. Movement of the piston stem 25 leftward in the guide slot 2-53 of the valve body 14 of the multiple position cock 4 releases the said piston stem from seating in one or the other of the locking slots 22 and 23 such that the plug valve l5 may be rotated to either position A or B (indicated at the handle 16) as desired to supply fluid under pressure to passage "15 selectively from either passage 17 or 9 and feed groove 21.

Although the handles 6 and it are shown and described herein as in their respective full pressure positions, operation of the equal pressure valve 3 to supply fluid under pressure to the locking cylinder 24 can be effected in a like manner regardless of the positioning of the two handles 5 and in, as long as they are both positioned to supply equal fluid pressures. For example, assume the pressures of fluid supplied to the pipes 8 and 12 are decreased from a pressure of say psi. toward a zero pressure as the handles ti and 1%, respectively, are moved to the left in a counterclockwise motion. Also assume a pressure of '10 psi. supplied to the passage 18 of the multiple position cock would cause the adjusting device (not shown) to cause the propeller pitch to be at one extreme angle of incidence indicating a full ahead speed, and a pressure of 60 psi. supplied to the passage 18 of the multiple position cock WOlld cause the adjusting device to cause the propeller pitch to be at an opposite extrerne angle of incidence indicating a full astern speed, with the angle of incidence adjustable from one extreme (full ahead) to the opposite (full astern) as the fluid pressure supplied to passage 18 is increased. Thus, if both handles 6 and it? were at any like positions supplyin any equal pressures, the multiple position cock could be rotated to shift control from the engine room to the bridge and vice versa. If, however, one of the'handles, say handle 6, is positioned to supply a low fluid pressure (which would result in a high speed forward), and the handle ill were positioned to supply a high fluid pressure (which would result in a high speed astern), the unequal pressures supplied to the equal pressure valve would prevent movement of the multiple position cock and thereby prevent shifting of control from one control valve to the other, in a manner now described.

If the fluid pressures supplied to the pipes 32 and 33 are unequal, it can be seen that the fluid pressures in the chambers 39 and 4% will likewise be unequal to cause the diaphragm 38 and connected rod 41 to be moved vertically either upward or downward, dependent on which of the fluid pressures in the chambers 39 and 4t} predominates. The resultant vertical movement of the rod 41 and cam 74 will permit the ball-shaped knob 73 of the lever 71 to ride down one or the other of the tapered surfaces 76 or 77 of the cam 74, dependent on the direction of vertical movement of the rod 41, to cause counterclockwise rotation of the lever 71 due to the force of the spring 61 acting leftward through the piston 56 against the ball-shaped knob 72 on the lever 71.

When the lever 71 moves counterclockwise as just de scribed,'the piston 56 simultaneously moves to a lefthand position in which a series of different events occur simultaneously, as follows:

(a) the spring 68 acting on the exhaust valve ball 66 moves the intake and exhaust valve 64 to the left with the moving piston 56 until the intake valve ball 67 seats in the passage 63 to prevent further supply of fluid under pressure therethrough;

(1)) once the intake valve ball 67 is seated, continued movement to the left of the piston 56 by the spring 61 moves the piston face and the passage 6% therein away from the exhaust valve ball 66 to open the passage 6% between the chamber 54 and the chamber 5'7 in the piston stem 55, and

(c) the outlet 58 in the piston stem 55 aligns with the exhaust port 59 in the housing 36.

It can thus be seen that the leftward movement of the piston 56 effects cutoif of the supply of fluid under pressure from pipe 34 to the chamber 27 of the locking cylinder 24 and simultaneously effects venting of said chamber to atmosphere by way of pipe 30, chamber 54, passage 60, chamber 57, outlet 58 and port 59.

With chamber 27 of the locking cylinder 24 vented, the spring 29 moves the piston 26 to the right thereby moving the stem 25 through the groove 20 to seat in either one of the locking grooves 22 or 23, determined by positioning of the plug valve 15 by rotary movement of the handle 16, to cause the plug valve 15 to be locked in the position desired.

Rotary movement of the plug valve 15 can thus be effected only when the handles 6 and 10 of the respective control valves 1 and 2 are positioned to-supply fluid under equal pressures to the respective pipes 32 and 33 to in turn reposition the diaphragm 38 of the equal pressure valve 3 to its central position described hereinbefore.

Although this apparatus is described herein as adapted to shipboard operation, it can be seen that it could be readily adapted for other adjusting devices, as for example motor controls in locomotives with two engineers control stations.

Having now described the invention, what we claim as new and desire to secure by Letters Patent, is:

1. Apparatus for pneumatic equal pressure change-over protection on a multiple position cock of the type utilized to control an adjusting device, said apparatus including a plurality of control valves, a multiple position cock having a rotary member selectively positionable to supply fluid under pressure to an adjusting device, means for pre venting rotation of said rotary member including locking cylinder means having a piston slidably mounted therein, piston stern means extending from said piston to said rotary member of said multiple position cock, said piston forming within said cylinder at pressure chamber adapted to be selectively supplied with fluid under pressure or vented to atmosphere, said piston stem being operably positioned in rotation preventing engagement with said rotary member of said multiple position cock when said pressure chamber of said locking cylinder means is vented to atmosphere and operably positioned out of engagement with said rotary member of said multiple position cock when said pressure chamber of said locking cylinder means is supplied with fluid under pressure, and a pressure differential operated valve means having a diaphragm means subject on one side thereof to a fluid pressuresupplied by one of said control valves and subject on the other side thereof to a fluid pressure supplied by another of said control valves, said pressure differential operated valve means operably responsive to simultaneous supply of fluid under equal pressures from each of said control valves to supply fiuid under pressure to said pressure chamber of said locking cylinder means, and operably responsive to simultaneous supply of fluid under unequal pressures from each of said control valves to eflect venting of 'said pressure chamber of said locking cylinder means.

2. In combination:

(a) a fluid pressure source,

(b) two different control valve devices arranged to supply respective control fluid pressures from the said fluid pressure source for a desired control purpose,

(0) a change-over valve device shiftable to different operative positions for establishing communication of said control fluid pressure alternatively from the control valve devices for the desired control purpose, and

(d) safety interlock apparatus for preventing operation of the change-over valve device from one operative position to another unless the fluid pressures supplied by both said control valve devices are equal, said apparatus comprising:

(i) a locking cylinder responsive respectively to fluid pressure supplied thereto from the fluid pressure source to unlock the said change-over valve device for eifective operation from one operative position to another as desired and responsive to venting of fluid pressure therefrom to lock the said change-over valve device against operation from one operative position to another, and

(ii) pressure differential operated valve means subject in opposing relation to the control fluid pressure supplied by said control valve devices respectively for supplying fluid pressure from the fluid pressure source to said locking cylinder so long as the pressures supplied by the said control valve devices are equal, and for venting fluid pressures from the locking cylinder when said pressures are unequal.

References Cited in the file of this patent UNITED STATES PATENTS 1,708,267 Godfrey Apr. 9, 1929 1,965,237 Hawkins July 3, 1934 1,984,828 Fornwalt Dec. 18, 1934 2,534,509 Franck Dec. 19, 1950 2,659,203 Carlson Nov. 17, 1953 2,664,915 Drinker Jan. 5, 1954 

1. APPARATUS FOR PNEUMATIC EQUAL PRESSURE CHANGE-OVER PROTECTION ON A MULTIPLE POSITION COCK OF THE TYPE UTILIZED TO CONTROL AN ADJUSTING DEVICE, SAID APARATUS INCLUDING A PLURALITY OF CONTROL VALVES, A MULTIPLE POSITION COCK HAVING A ROTARY MEMBER SELECTIVELY POSITIONABLE TO SUPPLY FLUID UNDER PRESSURE TO AN ADJUSTING DEVICE, MEANS FOR PREVENTING ROTATION OF SAID ROTARY MEMBER INCLUDING LOCKING CYLINDER MEANS HAVING A PISTON SLIDABLY MOUNTED THEREIN, PISTON STEM MEANS EXTENDING FROM SAID PISTON TO SAID ROTARY MEMBER OF SAID MULTIPLE POSITION COCK, SAID PISTON FORMING WITHIN SAID CYLINDER A PRESSURE CHAMBER ADAPTED TO BE SELECTIVELY SUPPLIED WITH FLUID UNDER PRESSURE OR VENTED TO ATMOSPHERE, SAID PISTON STEM BEING OPERABLY POSITIONED IN ROTATION PREVENTING ENGAGEMENT WITH SAID ROTARY MEMBER OF SAID MULTIPLE POSITION COCK WHEN SAID PRESSURE CHAMBER OF SAID LOCKING CYLINDER MEANS IS VENTED TO ATMOSPHERE AND OPERABLY POSITIONED OUT OF ENGAGEMENT WITH SAID ROTARY MEMBER OF SAID MULTIPLE POSITION COCK WHEN SAID PRESSURE CHAMBER OF SAID LOCKING CYLINDER MEANS IS SUPPLIED WITH FLUID UNDER PRESSURE, AND A PRESSURE DIFFERENTIAL OPERATED VALVE MEANS HAVING A DIAPHRAGM MEANS SUBJECT ON ONE SIDE THEREOF TO A FLUID PRESSURE SUPPLIED BY ONE OF SAID CONTROL VALVES AND SUBJECT ON THE OTHER SIDE THEREOF TO A FLUID PRESSURE SUPPLIED BY ANOTHER OF SAID CONTROL VALVES, SAID PRESSURE DIFFERENTIAL OPERATED VALVE MEANS OPERABLY RESPONSIVE TO SIMULTANEOUS SUPPLY OF FLUID UNDER EQUAL PRESSURES FROM EACH OF SAID CONTROL VALVES TO SUPPLY FLUID UNDER PRESSURE TO SAID PRESSURE CHAMBER OF SAID LOCKING CYLINDER MEANS, AND OPERABLY RESPONSIVE TO SIMULTANEOUS SUPPLY OF FLUID UNDER UNEQUAL PRESSURES FROM EACH OF SAID CONTROL VALVES TO EFFECT VENTING OF SAID PRESSURE CHAMBER OF SAID LOCKING CYLINDER MEANS. 